The present invention is related to hitch components that mount a towing vehicle to an agricultural tool to allow relative angular vertical articulation of the tool and towing vehicle.
For purposes of this disclosure, and as an aid in interpretation of the appended claims, the term "tool" should be taken to mean any unit of agricultural machinery that operates to perform a ground working function by use of implements moved along the ground by a towing vehicle. Examples of such "tools" are rod-weeders, harrows, plows, disc cultivators and the like. Examples of such implements are the rod of a rod weeder, the spring teeth of a harrow, the moldboard of a plow, and the discs of a cultivator.
Modern farm tractors have substantial pulling capability and can pull wide, heavy tools on frames that span transverse distances of sixty to seventy feet. Such tools substantially reduce the amount of time required in the field. The new, extra large tools are not without special problems, however, both during transport and when in use.
Transport of a tool from one field to another often requires travel on a public roadway. Load width requirements on such roads dictate that some special provision be made to reduce the overall width of a tool. In response, tools have been made to fold into a narrow transport configuration. The weight of the tool is therefore necessarily transferred to wheels set at the narrow, transport stance. The load on the wheels can often be in a somewhat precarious balance and care must be taken to assure that the load does not begin wobbling during transit.
Another difficulty with modern wide farm tools is experienced in the field. The tongue or hitch connector between the tool and towing vehicle must have a length about equal to one-half of the width of the tool in order to provide sufficient control at the lateral tool ends. Therefore, a tongue of approximately thirty feet would be preferred with a tool sixty feet wide. This relationship presents no problem when the tool is drawn along a flat surface. However, in rough or rolling terrain, significant problems occur when the tool is on one hillside slope and the towing vehicle is progressing along another. The ground-working implements are either levered into or out of the ground by the long tongue.
The obvious solution of providing a shorter tongue leads to even more difficult problems in controlling the progression of the tool around curves. Lateral stability of the tool ends decreases with decreasing length of the tongue or hitch.
Another solution has been the suggested use of a pivoted tongue or hitch between the tool and towing vehicle. Such an arrangement will function well during field usage, but has very serious drawbacks when the tool is to be transported.
There remains a need, therefore, for some form of hitch assembly that can be positioned between the towing vehicle and tool that will facilitate field usage of the wide tool and that will allow safe transport of the tool when folded to its transport condition.
The present invention answers the above need by providing a hitch assembly that allows relative elevational motion of the towing vehicle and tool when in field use and that secures the implement, thereby minimizing the dangers associated with large implement transport. Additionally, the present invention provides other important features, such as vertical height adjustment and capability for tipping the tool as it is lowered to an operating position.
The present invention can be provided in three basic forms to accomodate various needs of a user. First, the present invention can be provided as a separable hitch assembly, including frames that will mount directly between the tool and towing vehicle. The hitch assembly can therefore be provided as an option on new equipment provided without tongue assemblies or having removable tongue assemblies. Secondly, the present invention can be manufactured as an integral part of an agricultural tool. Finally, the present invention can be provided as an attachment for existing tools by adding it to the existing tongue assembly.